Reviewed-by: acorn, sla

Summary: Add a notification to the GarbageCollectorMXBeans
Reviewed-by: acorn, mchung

Summary: Move initialization of the '_instance' field to avoid race with ServiceThread start.
Reviewed-by: dholmes, kamg, never, dsamersoff, ysr, coleenp, acorn

6766644: Redefinition of compiled method fails with assertion "Can not load classes with the Compiler thread"
Summary: Defer posting events from the compiler thread: use service thread
Reviewed-by: coleenp, dholmes, never, dcubed